Lead alloys



Patented Jam 3, 1939 UNITED STATES LEAD ALLOYS Jesse 0. Better-ton,Metuchen, Albert J. Phillips,.

Plainfield, and Albert A. .Smith, Jr.. Metuchen,

N. J., assignors to American Smelting and Refining Company, New, York,N. Y., a corporation of New Jersey No Drawing. Original applicationMarch 19,

1937, Serial No. 131,860. Divided and this application September 28,1938, Serial No. 232,092

2 Claims (Cl. 75-167) This invention relates to lead alloys and pro-Vides certain new and novel lead alloy composi-' tions which, by reasonof the properties they possess and exhibit, are definitely superior foruse 5 in the manufacture of such lead products as battery grids, cablesheathing, etc.

Broadly speaking, the invention may be said to provide ternary alloys oflead, calcium, and magnesium possessing certain highly beneficialphysical properties, and alloys comprising the base alloy of lead,calcium and magnesium with at least one additional alloying constituentimparting further desired properties to the alloy while at the same timeretaining or enhancingthe beneficial physical properties possesed by thebase alloy itself. I

More specifically, the invention provides alloys of lead, calcium andmagnesium in which the combined calcium and magnesium content does notsubstantially exceed 0.4% of the alloy with the magnesium content beingwithin the approximate limits of one quarter to three times the calciumcontent. While 0.03% to 0.05% each of calcium and magnesium ispreferred, compositions containing magnesium and calcium within thelimits of 0.01% to 0.3% and 0.01% to 0.1%, respectively, may beemployed.

Among metals which may be added to the leadmagnesium-calcium compositionare cadmium, copper, mercury and tin, all of which modify the behaviorof the alloy under corrosive influences without adversely affecting thefundamental physical nature of the ternary alloy. In addition copperstiffens the alloy moderately and acceler- 3 ates its aging; mercuryimproves its lustre and to a moderate extent its casting properties; tin

slightly improves its fluidity and casting properties. The amount ofmodifying or improvement metal which may be incorporated should fall 40within the approximate limits of 0.03% to, 3% with a minimum of aboutthree or four times the magnesium content.

The superior properties exhibited by the alloys of the invention arebest shown by the following data comparing same with several of theconventional alloy compositions available and often recommended forvarious specific purposes:

Brinell hardness 50 Lead alloyed with- Material tested 037 M 8% Sb 05%Ca ,52 i

Castings es" thlck 12.1 7.0 5. 2 Above aged 21 days at 30 C- 12.9 8.013.4 Same heated 2 hours at 100 C 13.4 9. 5 15.4 Grid castings )z" thick11.8 5.0 5.0 Above aged 21 days at 30 C l3. 8 11. 4 14. 8 Same heated 2hours at 100 C 14. l2. 15. 4

The above data clearly show that the new magnesium-calcium alloy isreadily hardened withoutelaborate heat treatment to a value equal to orbetter than that of antimonial-lead grid metal, the latter in turn beingsuperior to the calcium-lead alloy.

Tensile strength (lbs/sq. in.)

The superior strength of the rolled lead-magnesium-calcium sheet metalis quite evident from the above data and the high strength valuesdeveloped by simply aging 9. rolled strip, either at room or an elevatedtemperature, are quite remarkable.

Composition stability In almost any process in which metal is cast thereis always a certain amount of material in the natureof risers, gates,spillage and spoilage which must be returned to the process withoutspecial treatment or material loss if reasonably low costs are to beobtained. In the manufacture of storage battery grids the weight ofmaterial that must be remelted commonly approximates the weight ofsatisfactory grids produced but fortunately ordinary antimonial gridmetal can be repeatedly remelted without a very great change incomposition. This is illustrated by the following test in which gridmetal analyzing 7.83% Sb and 0.222% Sn was tested in a special machineequipped with a revolving paddle which swept the surface of the moltenmetal (temperature 355 C.) at exactly 100 R. P. M. for 10 minutes. Atthe end of the test the composition analyzed 7.77% Sb and 0.215% Sn.Applying the same test to a calcium-lead alloy containing initially 047%calcium, the calcium content dropped to 023% calcium which represented aloss of 50% of the vital alloying constituent. However, when the testwas applied to a calciummagnesium-lead alloy of the present inventionwhich contained 047% Ca and .20% Mg, the calcium and magnesium contentswere only very calcium-lead alloy suffered a decrease in' its 0511- clumcontent from 05% down to 005% with the same treatment.

Fatigue properties I The following table illustrates the fatigueproperties of several typical lead alloys as compared with themagnesium-calcium-lead alloy of the invention modified with tin:

Composition xa 's 7 395 3? 0. 700 8 1,000 0.038% Ca, balance Pb 1,4000.32% Sn, 045% Ca, 026% Mg, balance Pb 2 200 All tests were for20,000,000 reversals on a rotating beam machine at 2,000 B. P. M.

Creep tests The following creep data were obtained from tests conductedat room temperature for periods of from 1 to 4 years and illustrate themarked superiority of the magnesium-calcium base alloys to all others:

Lead alloyed with Time to creep 1% g 33 Days . 350 190 175 233 220 232240 437 1, 200 578 290 700 More than 1,200 732 Corrosion resistanceCorrosion resistance of any series of alloys is very difficult toevaluate because an alloy that is superior in one particular set ofcircumstances may be inferior in another. For instance, in batterystrength sulphuric acid a lead alloy containing 04% Mg and .05% Ca wasfound to have excellent corrosion resistance as measured by loss inweight but suil'ered from a peculiar penetration of the alloy in about 3months time when the temperature was raised to 70 C. However, thisdimculty was completely avoided by adding 0.25% tin to the alloy with noloss in physical properties. A lead alloy containing 03% Mg,

04% Ca and Sn was found to be equal to regular 8% antimony grid metal ingeneral corrosion resistance and superior to it for battery purposes dueto the former s freedom from the evils of sulphation and galvanic actionwhich accompany the use of antimonial lead grid metal.

From the data herein adduced, it will be readily apparent that thealloys of the invention possess and exhibit properties 'which ideallyfit them for numerous uses. Accordingly, while their value has beenemphasized with respect to their use as grid metal, it will beunderstood that they may be successfully utilized in many other fields.

The alloy compositions of the invention may be readily compounded byconventional processes employed by those skilled in the art forproducing other lead alloys, as, for example, by simply incorporatingthe requisite amounts of the alloying constituents in a proper quantityof molten lead without any particular regard to the sequence of theiraddition. Once compounded, the new alloy composition can be fabricatedby well known methods.

This application is adivision of the co-pending application of Jesse O.Betterton, Albert J. Phillips and Albert A. Smith, Jr., Serial No. 131,-860, filed March 19, 1937.

What is claimed is:

1. An alloy composed of 0.01% to 0.1% calcium, 99.98% to 99.6% lead, and0.01% to 0.3% magneslum.

2. A battery grid containing about 0.01% to about 0.1% calcium and about0.01% to about 0.3% magnesium, the balance being substantially all lead,characterized by its hardness and high tensile strength.

JESSE O. BETTERTON. ALBERT J. PHILLIPS. ALBERT A. SMITH'. JR.

